It's a simple concept, really. Under normal circumstances, the clothes and hair that surround most of our bodies trap a thin layer of warmth around us (below). Warmth that comes from our own natural body heat of about 98.6 degrees. But when the wind blows, things change.
That layer of heat can simply be blown away (below). That will make things feel colder right away. Combine that with the evaporative cooling effects of the wind across our skin, accelerating the evaporative cooling process, and you get the 'wind chill' factor... what it actually feels like to the human body.
Tuesday morning, we will experience wind chills temps in the mid to low 20's. Cold, almost dangerously cold by Houston standards. To protect yourself wear multiple layers of clothes, cover up as much exposed skin as possible and wear a scarf and hat to help trap more of your body's own warmth.
A light freeze is expected both Wednesday and Thursday mornings. That's when you'll want to have sensitive plants like small citrus and tropical plants covered up from the freezing temps.